110 Couthouy’s New Species of Mollusca 
posed by Sowerby, and is undoubtedly valid. Two 
species only have been discovered, previous to the pre- 
sent, T. Sowerbiénsis, Lesson, from Melville’s I., Arctic 
Seas, and T. borealis, Sowersy, from Coast of New- 
foundland. A figure of the latter is given in pl. ix, figs. 
6, 7, vol. iv. of Zool. Jour. which differs principally 
from ours in being much broader, having but two ribs 
instead of four or five, and the setaceous processes being 
much more conspicuous. The epidermis is also de- 
scribed as corneous, while that of our species may with 
more propriety be termed coriaceous. The difference 
is so constant, that I cannot but consider them as distinct 
species. 
Considerable numbers of this shell were taken from 
the entrails of fishes, caught between Cape Ann and 
Cape Cod. It varies very considerably in different 
stages of growth. In young specimens the lip terminates 
abruptly, at its juncture with the columella, while in 
adult individuals it is continuous and reflected upon the 
columella, in such a manner as almost wholly to con- 
ceal the umbilicus. The general characters of this shell 
would seem to indicate its vicinity to the Purpure. 
In addition to the species described in the preceding 
pages, the following have been observed in our waters, 
which are not upon the list prepared for Prof. Hitchcock, 
by the Society, in 1835. 
Modiola discors, Lin. Stomachs of fish in our Bay. 
* — discrepans, SE * A 
Valvata tri-carinàta, Say. Wenham Pond. 
Nàtica immaculáta, Totten, from fishes in all parts of 
the Bay. 
Galericulum levigatum, Brown. 
e ovdtum, ^ do. 
